As a follow-up to my post above, obviously if you ordered a new Alaskan for a step-side truck bed there would not be any plumbing exiting the lower section of the camper on either side except for the overflow and the drain for the fresh water tank, waste water would exit the rear of the camper. By the same token, fresh water intake and sink drain would be located on the flat section of the upper part so it over hangs the truck bed.
Just goes to show you that options were available at least at the Sun Valley shop where my Alaskan was built.